1. Field of the Invention
The present invention generally relates to a centrifugal dryer for removing surface moisture from pellets of resin material having a diameter generally ranging between approximately 0.015 to approximately 0.25 inches received from an underwater pelletizer. More specifically, the present invention relates to a dryer which is constructed with smaller dimensions enabling it to effectively operate at low volume rates and be easily assembled and disassembled to facilitate cleaning and replacement or interchange of components with its overall size enabling it to be effectively used in small applications, especially laboratory applications.
2. Description of the Prior Art
Centrifugal pellet dryers are well known and have been successfully used for many years to separate water from a water and pellet slurry and remove surface moisture from the pellets in order to provide relatively dry surfaces on the pellets for subsequent use. Previously known centrifugal pellet dryers are used for the purpose of removing surface moisture from pelletized products and are usually a relatively large machine for producing a large volume of dried pellets. The following U.S. patents relate to centrifugal pellet dryers:
4,476,019 5,187,880 5,611,150 4,570,359 5,505,537
The centrifugal pellet dryers disclosed in the above prior patents are primarily used in high volume production of dried pellets and are not practical for operation at low rates of production and are not sized to use in a laboratory application or other small operations.
Accordingly, the present invention seeks to overcome this deficiency in the prior centrifugal pellet drying constructions by incorporating unique features not shown in the prior art. For example, the pellet dryers of the prior art do not have a sectional housing with the sections being connected together by bolted external flanges for easy separation and access to the internal components. The above patents also fail to disclose a centrifugal pellet dryer having a base section attached directly to a tank for receiving the water from the water and pellet slurry thereby eliminating the necessity of using piping systems to drain water from the dryer. In addition, the prior art does not disclose a centrifugal pellet dryer in which the rotor is supported from a single upper bearing with the lower end of the rotor being rotably guided by an alignment bushing which is self lubricating and is cooled by the water of the water and pellet slurry thereby eliminating the need for providing a sealed bearing or other special device to protect a bottom bearing from the water. Still another feature not shown in the prior art is the use of a cylindrical screen in a centrifugal pellet dryer which telescopically engages a recessed edge of cup-shaped support members at the top and bottom ends of the screen and is supported by a pair of holding clips in the form of hooks to engage supporting pins on the upper cup-shaped support. Also, the prior art does not disclose the use of a lift device to assist in lifting and supporting the major components away from the base section to facilitate removal, cleaning and replacement of the dryer components.